This disclosure applies particularly to pad tools, caliper tools, sensing tools, and placement tools, where a mechanism permits the tool to modify its shape to move closer to the wellbore. The mechanism usually opens the link or arm using means either active (e.g., piston, screw, sliding link) or passive (e.g., spring, gravity, friction of wellbore, fluid movement). See, for example, U.S. Pat. No. 6,702,010 issued 9 Mar. 2004 to Yuratich et al. and U.S. Pat. No. 4,979,585 issued 25 Dec. 1990 to Chesnutt, for examples of various similar devices.
In the well logging art, the logging direction is usually unidirectional. This means that the tool sensing section is not symmetrical, having a preferred way of logging (usually upwards). Therefore, the logging can generally be performed in only one direction, usually during the ascent (or egress) and not during the descent (or ingress).
Being able to perform logging either during the descent, or ingress, has numerous advantages. These advantages are multiplied if logging can be performed both during ingress and egress from the wellbore. Applicant uses ascent and descent, or ingress and egress, to indicate relative longitudinal movement of the drill string and is not limited herein to up and down movement. The down in lateral horizontal wells can, in fact, be up. Moreover, longitudinal movement may, in fact, be lateral in a lateral well. In particular, logging during ingress of the wellbore permits the capture of a full repeat file; or, a combination file if the tool is operating properly both on ingress into the wellbore and egress from the wellbore. Logging during ingress permits data collection and verification during ingress, and increases the probability of identifying a problematic wellbore situation before a failure occurrence. This is particularly desirable in deviated or horizontal wells where tool failure has historically shown a higher probability to occur due to the conveying modes employed (drill pipe conveyed, tractor conveyed, coil-tubing convey, etc.), or due to experienced high pressure and temperature as the tool approaches Total Depth.
The apparatus and method of the current disclosure permits a tool, whether utilizing pad, caliper, sensing, or placement modalities, to adapt to the logging direction, thereby allowing an operator to log in both directions (ingress and egress) while also providing more accurate, less damaging, and more continuous contact of sensing devices on the arm or extension touching or osculating the wellbore wall.